The invention relates to value-added telecommunication services, to be more specific, an interface card and a CTI system applying interface cards.
Applications of Computer Telephony Integration (CTI), especially value-added telecommunication services, generally require the system to have a large channel capacity and sufficient expandability. Due to limited processing capabilities of single unit and requirement of system reliability, the overall CTI system usually has to be distributed in multiple chassis, which demands interconnection of the distributed chassis. In CTI application, interconnection of multiple computers is realized with interface card. There are three commonly used interface cards in the market: CT-BUS extension, ATM interface conversion and Ethernet interface conversion.
CT-BUS extension interface card enables interconnection of BUS between chassis by directly converting unipolar CT BUS signals in a CTI single unit into RS-485 signals. As CT BUS has a plurality of signal cables, there are a plurality of pairs of connection cables between chassis. All the chassis are actually connected to the same CT BUS, therefore the transmission distance has to be small (less than one meter) and the requirement for signals is very strict. It features complicated installation and usage, and low reliability.
ATM interface conversion interface card enables interconnection of multiple computers by merging and combining CT BUS data in a CTI single unit into ATM packets and switching to optical fiber transmission via ATM optical port. It features a long connection distance and good expandability. But its application is limited due to high cost and complicated usage.
Ethernet interface conversion interface card enables interconnection of multiple computers via Ethernet by packing CT BUS data to be switched in a CTI single unit with a specific Ethernet packet processor. It features simple usage, easy connection, a long connection distance and good expandability, only requiring a common twisted pair cable for interconnection. However, its cost per channel is high, which can lead to an extremely high cost when it comes to application of large channel capacity.